powerpc: move math-emu over to arch/powerpc

Towards the goal of having arch/powerpc not build anything over in arch/ppc
move math-emu over.  Also, killed some references to arch/ppc/ in the
arch/powerpc Makefile which should belong in drivers/ when the particular
sub-arch's move over to arch/powerpc.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/math-emu/mtfsb1.c

@@ -0,0 +1,18 @@
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <asm/uaccess.h>
+
+#include "soft-fp.h"
+
+int
+mtfsb1(int crbD)
+{
+	if ((crbD != 1) && (crbD != 2))
+		__FPU_FPSCR |= (1 << (31 - crbD));
+
+#ifdef DEBUG
+	printk("%s: %d %08lx\n", __FUNCTION__, crbD, __FPU_FPSCR);
+#endif
+
+	return 0;
+}